Accidental transients in fusion reactors, such as the in-vessel loss-of-coolant accident
(LOCA) considered here, are generally analyzed using system-level codes. However,
because of their lumped nature, such tools cannot predict local pressure and temperature
values, which are instead of interest to assess the integrity of the vacuum vessel (VV)
structures. It is then fundamental to prove that the system-level tools' predictions are at least
conservative. In this work, we analyze the helium flow inside the VV following a LOCA in the …

The in-vessel Loss-of-Coolant Accident (LOCA) is one of the design basis accidents in the
design of the EU DEMO tokamak fusion reactor. System-level codes are typically employed
to analyse the evolution of these transients. However, being based on a lumped approach,
they are unable to quantify localised quantities of interest, such as local pressure peaks on
the vacuum vessel walls, to which the failure criteria are linked. To calculate local quantities,
the 3D nature of the phenomenon needs to be considered. In this work, a 3D transient model …